A method is provided for coding at least one image split up into partitions, a current partition to be coded containing data, at least one data item of which is allotted a sign. The coding method includes, for the current partition, the following steps: calculating the value of a function representative of the data of the current partition with the exclusion of the sign; comparing the calculated value with a predetermined value of the sign; as a function of the result of the comparison, modifying or not modifying at least one of the data items of the current partition, in the case of modification; coding the at least one modified data item.
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1. A non-transitory computer-readable medium storing image data for decoding by a decoder, the image data comprising: a sign-data-hiding enabled portion of a bitstream; wherein the sign-data-hiding enabled portion is representative of at least one partition of an image split up into partitions; wherein a partition comprises a set of coefficients, and a particular non-zero coefficient of the set of coefficients is without a sign designation; wherein the sign designation of the particular non-zero coefficient is derived by: identifying a first non-zero coefficient within the set of coefficients; identifying a last non-zero coefficient within the set of coefficients; determining a count of coefficients from the first non-zero coefficient to the last non-zero coefficient including the first and the last non-zero coefficients; and in response to determining that the count is greater than 4: calculating a sum of amplitude information of non-zero coefficients in the set of coefficients; calculating, using the sum of amplitude information of the non-zero coefficients, parity data; and designating, on the basis of the parity data, a sign for the particular non-zero coefficient.
This describes a method for decoding image data stored on a computer-readable medium. The image data contains a specially-encoded section where the sign of certain coefficients has been intentionally hidden to improve compression. The image is first split into partitions. Within a partition, if the number of non-zero coefficients between the first and last non-zero coefficients (inclusive) is greater than 4, the process calculates a parity value based on the sum of the amplitudes (absolute values) of those non-zero coefficients. This parity value is then used to determine the sign of a specific non-zero coefficient, effectively decoding the hidden sign data.
2. A method for encoding a sign-data-hiding enabled data signal representative of at least one image split up into partitions, the method comprising: setting a partition of an image comprising a set of coefficients; identifying a first non-zero coefficient within the set of coefficients; identifying a last non-zero coefficient within the set of coefficients; determining a count of coefficients from the first non-zero coefficient to the last non-zero coefficient including the first and last non-zero coefficients; and in response to determining that the count is greater than 4: calculating, using the sum of the amplitude information of the non-zero coefficients, parity data; calculating, using the sum of the amplitude information of the non-zero coefficients, parity data; selecting a particular non-zero coefficient to be encoded into the bitstream without a sign bit; when the parity is even and the sign of the particular non-zero coefficient is negative, modifying a coefficient between the first and the last non-zero coefficient; and transmitting the modified set of coefficients.
This describes a method for encoding an image by hiding the sign of certain coefficients. The image is divided into partitions, each containing a set of coefficients. The encoder identifies the first and last non-zero coefficients in a partition. If the count of coefficients between them (inclusive) exceeds 4, a parity value is calculated using the sum of the amplitudes of the non-zero coefficients. A particular non-zero coefficient is then chosen to have its sign hidden. If the calculated parity is even but the chosen coefficient's sign is negative, another coefficient between the first and last is modified (presumably by changing its sign) to ensure the parity reflects the hidden sign. The modified coefficients, including the coefficient with the hidden sign, are then transmitted, without explicitly transmitting the sign of the specific coefficient.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
April 18, 2016
July 11, 2017
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